Four stages

The Four Stages or Four Levels are from the book Discussion of Warm Diseases by Ye Tian Shi, written in the years 1667-1746.

Additional recommended knowledge

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The stages are in order from surface to deep internal and from "light" sickness to death:

• Wei level treated by releasing the exterior (diaphoresis)
  

wind-heat
summer-heat
damp-heat
dry-heat

• Qi level treated by dispelling heat and promoting body fluids
  

Lung heat (heat in chest and diaphragm)
Stomach heat
Intestines dry-heat
Gall-bladder heat (heat in the lesser yang)
Stomach and Spleen damp heat

• Ying (Nutritive qi) level treated by cooling fire and tonifing the yin
  

Heat in Nutritive qi portion
Heat in Pericardium

• Blood level treated by tonifing the yin and qi and stopping bleeding.

Heat Victorious moves blood
Heat victorious stirs wind
Empty wind agitates in the interior
Collapse of yin
Collapse of yang
Separation of yin and yang (Death)

References

• Maciocia, Giovanni, The Foundations of Chinese Medicine: A Comprehensive Text for Giovanni
• Maciocia, Giovanni, The Practice of Chinese Medicine (c) 1994
• Tyme, Student Manual on the Fundamentals of Traditional Oriental Medicine, second ed.
• Douglas E Knapp, LAc MSAOM Bastyr University TCM class notes